Prostate cancer is the most common cancer diagnosed in the United States today. While most men can be cured if the prostate cancer is still confined within the gland, prostate cancer still claims nearly 40,000 lives each year. In order to reduce the death rate of cancer, it must be diagnosed at earlier stages. Prostate cancer typically spreads to the pelvic lymph nodes initially, and later attacking the bony skeleton. There is growing evidence that shows a survival advantage for prostate cancer patients if a cancerous pelvic lymph node is diagnosed at a microscopic size before it could be detected radiographically. That is, the surgical removal of a lymph node that has a microscopic focus of prostate cancer may impact that patient's overall survival. An ideal sentinel node imaging agent would exhibit rapid clearance from the injection site and sustained uptake by the sentinel node. Technetium-99m-labeled DTPA-mannosyl-dextran is a new radiotracer that has been shown in a Phase I Clinical Trial in breast cancer to have these properties. The purpose of this study is to test this agent in prostate cancer. The FDA Guidance for Industry states that the purpose of a Phase I clinical trial of a medical imaging agent is: 1) to obtain preliminary evidence of efficacy, and 2) to assessment of its biological safety. Therefore, this project will have two primary specific aims and one secondary specific aim. Data for Specific Aim One will test the hypothesis that [99mTc]DTPA-mannosyl-dextran biodistribution will provide acceptable absorbed radiation doses at an injected radiation dose that yields adequate imaging and intra- operative mapping. We will test this hypothesis at three molar dose levels of our new agent. Data for Specific Aim Two will include subject observation and clinical laboratory tests obtained before and after administration of our new agent. We will test the hypothesis that our new agent does not alter any vital signs or clinical laboratory tests. As a secondary goal Specific Aim Three will determine the distribution of [99mTc]DTPA-mannosyl-dextran within the lymph node basins draining the prostate gland. We will note the number and location (basin) of each sentinel node. If a high percentage of sentinel nodes are detected outside of the obturator fossa, this specific aim will provide the motivation to proceed with a Phase II clinical trial. Previous work in Europe, using an albumin-based colloid, reported that 76% of the sentinel nodes resided OUTSIDE of the lymph node basins (obturator fossa) routinely excised for prostate cancer staging. [unreadable] [unreadable] [unreadable]